Still under construction...
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Q: What softphone work with siproxd?
A: The goal is that every softphone (that is SIP compliant) should be
able to work via siproxd. Tested and/or reported to work so far:
- linphone (http://www.linphone.org)
- kphone (http://http://www.wirlab.net/kphone/)
- MSN Messenger
- Grandstream BudgeTone series
- X-Lite (http://www.xten.com)
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Q: Is it possible from a remote computer to call the inbound computer?
A: Yes, see also next question.
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Q: What SIP address must the remote computer use to make a call?
A: Scenario
--------
private IP address range : Internet
10.0.0.x : (public IP address range)
:
: foo.bar.org xxx.org
+-------------+ +--------------+ +-------------+
! !.10 .1 ! masquerading ! publicIP ! !
! IntHost !-------------! Firewall !------------>>! externalHost!
! ! eth0! !ppp0 ! !
+-------------+ +--------------+ +-------------+
user: johndoe user: test
- IntHost is running an SIP softphone (like linphone, kphone)
- The SIP address used by IntHost is sip:johndoe@foo.bar.org
- The softphone on IntHost is configured to register at siproxd
running on the firewall host (10.0.0.1) as sip:johndoe@foo.bar.org
- foo.bar.org is the domain name corresponding to the public IP address
of the firewall (eg use some dynamic DNS service [1])
- externalHost does *not* register at siproxd running on the firewall host.
The relevant part of the configuration (linphone) of IntHost
then looks like ($HOME/gnome/linphone):
[sip]
sip_port=5060
use_registrar=1
username=johndoe
hostname=foo.bar.org
registrar=sip:10.0.0.1
reg_passwd=
addr_of_rec=sip:johndoe@foo.bar.org
reg_expires=900
as_proxy=1
as_redirect=0
as_outbound=1
To make an outgoing call from IntHost simply use the SIP address of the
target ( -> sip:test@xxx.org).
test@xxx.org can make a incoming calls - it simply has to use the registered
SIP address of the softphone running on IntHost (sip:johndoe@foo.bar.org).
Siproxd will then rewrite and forward the incoming request to Inthost.
The externalHost does not need to know anything about the proxy. For the
user sip:test@xxx.org it looks as he directly sends the traffic to
foo.bar.org, siproxd then takes care about where to send it from there.
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Q: How does the registration and mapping of inbound clients work?
A: The mapping mechanism of SIP addresses works basically like:
Inthost sends a registration to siproxd with:
- a 'To:' address of the address to be registered (sip:johndoe@foo.bar.org)
(lets call this address the 'masqueraded' or 'public' address)
- a 'Contact:' address of the *true* address (sip:johndoe@10.0.0.10)
Siproxd then will basically 'just' substitute the true address by the
masqueraded address and vice versa. That means you can have multiple
IntHosts (each of them using a different user name) running at the
same time.
For an incoming call, siproxd will search its registration table for
the requested SIP address and so finds the internal host that belong to it.
This of course *requires* that the username part of the SIP address is
unique for each softphone that registers a the proxy (So this is more or
less the mechanism that you mentioned in your mail).
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Q: How does the RTP Proxy work?
A: The RTP proxy actually is quite simple. It does not use any RTP
protocol stack. All relevant code is located within rtpproxy.c.
The RTP proxy is running as a separate thread. It maintains a
list of active RTP transfers (rtp_proxytable).
Controlling (registering a new RTP data stream / removing a RTP stream)
is done via 2 service routines rtp_start_fwd() and rtp_stop_fwd() from
withing the SIP related part of siproxd.
When a session is established (INVITE, ACK), siproxd will fetch the
relevant information (UDP ports) from the SIP messages and
does a rtp_start_fwd().
This will create an UDP socket and binds it to the outbound interface
address (port number dynamically chosen withing the RTP port range).
In addition a entry into the rtp_proxytable will be made.
The RTP Proxy then *simply* does wait withing a select() to receive
a UDP datagrams on the specified ports and then sends them to the
local client. The RTP proxy does absolutely not care about WHAT data
is proxied, so it is not aware of RTP or any other high level stuff.
It is simply a binary forwarding of datagrams.
If the session is closed (BYE) the RTP stream will be stopped via
rtp_stop_fwd(). In addition, there exists a timeout supervision
(configurable) that will stop RTP streams that have been inactive
(no data received) for a specified time.
For each RTP data stream, also an RTCP stream will be handled (port
number of RTP strem +1).
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Q: Does siproxd need to be installed on the same host as the
firewall / NAT is running?
A: Not necesarily. Siproxd needs to know the public IP address, as this
address is included in the SIP signalling to establish a session. Also,
siproxd needs control on the allocation of UDP ports for sending/receiving
RTP data (some User Agents get into trouble/silence if the sending and
receiving UDP port is not the same)
However, siproxd does *not* interact with ipchains/iptables. The
requirement for the firewall rules is to allow port 5060 for incomming
UDP datagrams (SIP) as well as the UDP port range for RTP data as
specified in the config file (default 7070 - 7079).
One mode of operation is to run siproxd on the NAT host, using
different if_inboude and if_outbound interfaces.
The other method is to ruin siproxd "in front of" the NAT firewall.
For configuration details see the documentation (host_outbound).
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Q: How do I configure siproxd to use ICPHAINS based UDP masquerading
tunnels for proxying the incomming RTP traffic?
A: Since version 0.5.2, IPCHAINS and IPTABLES are no longer supported.
Use the RTP relay instead.
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Q: What types of operation does siproxd support?
A: Siproxd can be used in two ways:
1) Siproxd as outbound proxy:
- Configure your local client to register with some 3rd party service
like Sipphone, FWD, Sipgate or any other.
- Configure your local client to use siproxd as OUTBOUND PROXY
Note: In this case, the local client does NOT register with siproxd
but only with the external SIP restration service. The only condition
is that siproxd needs to stay in the path of communication, therefore
the local client must be configured as to use an OUTBOUND PROXY.
2) Siproxd as registrar:
If you don't want to use any 3rd party service, you can have your
local clients directly with siproxd. Only in this case you should
set-up accounts and passwords in siproxd.
- Configure you local client to register with siproxd. As AOR (address
of record) choose a user part as you want and a host part that
resolves to the public addess of the host running siproxd.
- DO use siproxd as outbound proxy
Note that siproxd has very limited capabilities when used as
registrar. So my recommendation is to use method 1) and go with
a real registrar.
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Q: How do I use siproxd as a pure outbound proxy, so I can register with my
SIP phone at a third party registrar?
A: Also Simple. Just configure your SIP phone to use siproxd as outbound
proxy and your 3rd party registrar as registrar. Siproxd will then
transparently handle (and if needed rewrite) the SIP traffic.
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Q: I have a Grandstream Budgetone-100 SIP phone. The SIP communication
seems to work properly (I can register, make and receive calls) but
I do not hear any audio. However, transmitting audio works.
A: Since version 0.5.2, IPCHAINS and IPTABLES are no longer supported.
Use the RTP relay instead. Grandstream SIP phones are now working
properly with the RTP relay.
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Q: I use Linux (kernel 2.4.x) with ipchains. However, siproxd
always complains "ERROR:IPCHAINS support not built in", why?
A: Since version 0.5.2, IPCHAINS and IPTABLES are no longer supported.
Use the RTP relay instead.
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Q: I have two local UA (SIP phones) connected to siproxd. I can
make outgoing calls and receive incoming calls to some other
SIP phones in the internet. However, making a call between the
two locally connected does not succeed, why?
A: Since Version 0.5.3 this is supported.
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Q: When I'm experimenting with siproxd, sometimes it is not enough to
restart siproxd to get rid of old junk.
A: Siproxd remenbers the registrations made by UAs in a seperate file.
Therefore, just restarting siproxd is not enough to get rid of them.
Of course eventually they will time out and be removed from the cache.
You also can delete the cache file manually.by default it is in
/tmp/siproxd_registrations.
- stop siproxd
- rm siproxd_registrations
- start siproxd
Also, with newer Linux Kernels (2.6.x with conntrack kernel module
loaded) there may be some state information stored within conntrack.
Stopp all SIP traffic (UAs, including siproxd) and wait about 5
minutes, then try again.
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Q: I have problems getting MSN Messenger 5.0 to work (using FWD
as 3rd party registrar).
A: First make sure that you have an SIP enabled MSN messenger, which
is a separate download from the non-SIP-enabled Messenger 5 at
http://www.microsoft.com/windows/messenger.
For the configuration, enter the local IP address of siproxd as the server
and 266xxx@fwd.pulver.com as your address. When the authentication
dialog comes up you must use your FWD_NUMBER (266xxx) and your password.
Messenger misleads you into typing FWD_NUMBER@fwd.pulver.com which
will fail...
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Q: Can you give an example configuration for kphone and FWD?
A:
(FWD_NUMBER is your FWD account number)
File->Identity
--------------
Full Name: My Name
User part of SIP URL: FWD_NUMBER
Host Part of SIP URL: fwd.pulver.com
Outbound Proxy: 192.168.1.1 <SIP->Socket
------------------------
Socket Protocol: UDP
Use STUN Server: No
Symmetric Signalling: No (may also be 'Yes')
Symmetric Media: No (may also be 'Yes')
STUN Server: << n/a
Request Period for STUN Server << n/a
Media Min Port: 7070 << depend of siproxd config
Media Max Port: 7080 (RTP ports)
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Q: If I update both inbound and outbound to
if_inbound = ppp0
if_outbound = ppp0
will this work ?
A: Very likely this will not work properly. Siproxd does masquerade User
Agents hidden behind a NAT firewall (inbound network) so they can access
other User Agents located in the public internet (outbound network).
Therefore there MUST be 2 networks connected to the host running
siproxd:
- Inbound network
- Outbound network
If you just want a proxy located in the public IP range you should not
use siproxd, but get a real SIP proxy server instead.
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Q: I can build siproxd, but when I try to start it, it fails with
something like:
$ siproxd -h
siproxd: error while loading shared libraries: libosipparser2.so.3:
cannot open shared object file: No such file ordirectory
A: Make sure you have correctly installed libosip2. If libosip2 is
installed somewhere else than the standard library paths, the
path MUST be included in the /etc/ld.so.conf file to tell the
dynamic linker where to search for libraries.
Try the following command:
$ /sbin/ldconfig -p|grep libosip
The output MUST be something like:
libosip2.so.3 (libc6) => /usr/lib/libosip2.so.3
libosip2.so (libc6) => /usr/lib/libosip2.so
libosipparser2.so.3 (libc6) => /usr/lib/libosipparser2.so.3
libosipparser2.so (libc6) => /usr/lib/libosipparser2.so
If not, libosip2 is not correctly installed.
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Q: I have two Internet connections, one is my main connection and the
second is my backup connection. Can I configure siproxd in a way
to handle both Internet connections (switch to the backup connection
if the other one fails)?
A: Siproxd itself does not include support for such a thing. However what
you can do is, use 2 different siproxd configuration files (with the
two different outbound interfaces configured). Then, if the main
interface goes down and you activate the backup connection, just
copy the second siproxd config file in place and restart siproxd.
Active registrations are not lost, as siproxd does save them at exit.
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Q: Scalability of siproxd?
A: In practice, stable operation of siproxd installations with more than
600 VoIP Accounts and more than 60 concurrent calls are being reported.
Multiple instances of siproxd may be run on the same server.